Conventionally, as a display device usable for a mobile information terminal, a liquid crystal display device and an organic EL (electroluminescence) display device are known. As the information terminal is reduced in size, these display devices are now required to reduce the size of a region other than a display region (so-called peripheral region). Recently, a technology of electrically connecting a line provided on the side of a front surface of a substrate and a line provided on the side of a rear surface of the substrate to each other via an opening formed in the substrate has been developed (Japanese Laid-Open Patent Publication No. 2010-8677).